going to HEAD of a tag goes to the wrong place

instead it goes to the head of trunk.

the revisions tab works correctly, ie. you can find the latest version of a file from a tag, but clicking on the Source tab takes you to HEAD of trunk instead of taking you to what you are looking at. Also, clicking on the file links in the directory tree should take you to the correct version.

this should (might?) be relatively easy to do using a simliar method to the revisions tab.